The present invention relates to a device for administration of a medicated aerosol via the lungs in accordance with the introductory clause of Patent claim 1.
The use of the respiratory tract for the administration of medicaments is gaining an ever-increasing importance. In this approach not only the application of new medicaments producing local effects for the treatment of pulmonary diseases is being developed, but also new therapeutic strategies are being designed which employ the lungs as the organ through which substances enter the body which produce systemic effects.
For the employment of the inhalation canal for the administration of medicaments continuously growing demands are made on the quality of the process of inhalation, which cannot be satisfied by the devices presently available in the market. For instance, it is necessary that the dosage of the medicament, which the physician has prescribed, will be administered as precisely as possible and in a reproducible manner, with the administered dose and its reproducibility depending substantially on the so-called respiration manoeuvre. The term xe2x80x9crespiration manoeuvrexe2x80x9d is to be understood to encompass the aerosol volume inhaled and the respiratory flow by which the patient performs the inhalation. With an appropriate selection of the respiration manoeuvre and the vaporiser or by matching the applied respiratory manoeuvre with the used vaporiser (particle size) the location of deposition of the medicament in the lungs could be selectively influenced so as to provoke a predominantly central or predominantly peripheral administration of the pharmaceutical.
A device of the general type outlined by way of introduction is disclosed already in the French Patent FR-A-2604093. What must be considered to be a disadvantage in this device is the fact that, on the one hand, the handling is complex and that, on the other hand, an administration dependent on the individual respiratory manoeuvre cannot be performed or realised only insufficiently.
As in every-day clinical routine the respiratory manoeuvre performed by the patient can usually be influenced only to a small extent or as the respiratory manoeuvre actually performed is almost entirely beyond control by the physicians a precise pre-determination of the respiratory volume and the respiratory flow in the inhalation of therapeutic aerosol were desirable because this would entail a substantial improvement of the inhalation therapy and its reproducibility. As a consequence, the administered dose could be estimated with a higher precision, with a precise observation of a particular respiratory manoeuvre, whilst at the same time savings in terms of costs could be achieved as well when particularly expensive pharmaceuticals are administered.
The present invention is therefore based on the problem of responding to the needs outlined in the foregoing with a device having a functionally simple design.
In accordance with this invention this problem is solved by the features defined in the claims. Preferred features providing an expedient improvement of the invention are also defined in the claims.
The inventive device expediently consists of an inhalation mouthpiece, an associated adjustable vaporiser and a compressed-air control valve through which a pre-settable volumetric flow of compressed air which can be supplied to the vaporiser containing the liquid medicament during an adjustable period of time, with a pressure sensor being provided for triggering the beginning of the vaporising operation of the vaporiser.
With the inventive device the patient is therefore enabled, with simple means, to inhale a precisely predetermined volume of a pharmaceutical substance at a precisely predetermined respiratory flow. With this device the separate air supply, which is already envisaged for therapeutic vaporisers in the clinical every-day routine, is expediently controlled in such a way that only a predetermined volume of air is output to the vaporiser at a predetermined flow rate. In accordance with the present invention hence the air of the vaporiser is adjusted to a pre-settable intensity of the volumetric flow, which the patient cannot take an influence on so that a constant flow will be achieved. The flow of supplied air is preferably turned on by an electronic controller over an invariably set period of time so as to achieve the administration of a precisely pre-determined air volume. On account of the length of a breathing pause, which can be determined with a special design of the invention, the total deposition of the medicament is expediently increased whilst the inter-individual variability of the deposited quantity is reduced.
For use of the device in practical application it is moreover expedient to provide a pressure gauge responsive to a suction pressure in the inhalation mouthpiece for triggering the beginning of the vaporising operation of the vaporiser
In accordance with a preferred configuration a controller is disposed upstream of the adjustable vaporiser for maintaining the volumetric flow constant, with a flow meter being preferably arranged downstream of the controller for control of a predetermined volumetric flow, which flow meter comprises a floating body in a specific embodiment. These provisions contribute expediently to an ensured controlled inhalation of therapeutic aerosols by means of the inventive device.
According to a preferred embodiment of the invention, the device comprises an electrical controller to control its operation, with a vaporising period and a pause interval being adjustable on the controller and with the electronic controller preferably including a visible and/or audible pause signal to indicate the pause between inhalation and exhalation, preferably in the form of a light-emitting diode. Moreover, the number of the vaporising periods can expediently be set in the form of a number of respiration cycles.
As far as the configuration of the vaporiser is concerned either a design in the form of a nozzle-type vaporiser with a separate compressed-air supply is envisaged, which can be turned on and off by means of the compressed-air control valve, with the separate compressed-air supply for the nozzle-type vaporizer being preferably branched off between the compressed-air control valve and the flow meter.
In an alternative design the vaporiser may be configured as ultrasonic transducer issuing high-frequency signals which can be directly controlled by the electronic controller.
The compressed-air control valve is preferably designed as solenoid valve, and a pressure reducer and a pressure gauge are arranged upstream of the control valve for adaptation to the individual compressed-air conditions.
In accordance with the invention a wide range of respiratory manoeuvres can expediently be opened up for medical applications with the simultaneous selection of the respiratory flow and the inhaled volume, with the opportunity to take an influence on the location of deposition in the lung in the desired manner. It is thus possible for the first time to deposit medicaments which are intended, for instance, to produce their effects in central areas of the lungs actually at the envisaged points.
Another advantage of the inventive device consists in the aspect that it permits an improvement of a routine performance of inhalations on patients in the clinical environment because, by virtue of the envisaged respiration triggering of inhalation, a patient will not encounter any problems with respect to the synchronisation of the start of operation of the vaporiser and hence the beginning of the inhalation operation. It is moreover expediently possible to reduce errors in inhalation substantially, which are due to improper handling of the vaporiser.
The invention will now be described in more details in the following with reference to the attached drawing wherein:
FIG. 1 is a schematic view of one embodiment of an inventive Device; and
FIG. 2 is a schematic diagram showing the components of the Embodiment of the invention according to FIG. 1.